分数（有理数）的四则运算PAT1088

2015-02-05
PAT- B1088. Rational Arithmetic (20)

http://www.patest.cn/contests/pat-a-practise/1088
  1 #include <iostream>
  2 #include <cmath>
  3 using namespace std;
  4 typedef long long LL;
  5 typedef struct Fraction{
  6     LL up,down;
  7 };
  8 LL gcd(LL a,LL b){
  9     return b==0 ? a : gcd(b,a%b);
 10 }
 11 Fraction reduction(Fraction res){
 12     if(res.down<0){
 13         res.down=-res.down;
 14         res.up=-res.up;
 15     }
 16     else if(res.up==0)
 17         res.down==1;
 18     else{
 19         LL d=gcd(abs(res.up),res.down);
 20         res.up/=d;
 21         res.down/=d;
 22     }
 23     return res;
 24 }
 25 Fraction add(Fraction a,Fraction b){
 26     Fraction res;
 27     res.up=a.up*b.down+a.down*b.up;
 28     res.down=a.down*b.down;
 29     return reduction(res);
 30 }
 31 Fraction sub(Fraction a,Fraction b){
 32     Fraction res;
 33     res.up=a.up*b.down-a.down*b.up;
 34     res.down=a.down*b.down;
 35     return reduction(res);
 36 }
 37 Fraction multi(Fraction a,Fraction b){
 38     Fraction res;
 39     res.up=a.up*b.up;
 40     res.down=a.down*b.down;
 41     return reduction(res);
 42 }
 43 Fraction divide(Fraction a,Fraction b){
 44     Fraction res;
 45     res.up=a.up*b.down;
 46     res.down=a.down*b.up;
 47     return reduction(res);
 48 }
 49 void showFraction(Fraction res){
 50     res=reduction(res);
 51     if(res.up<0)
 52         printf("(");
 53     if(res.down==1)
 54         printf("%lld",res.up);
 55     else if(res.up==0)
 56         printf("0");
 57     else if(abs(res.up)>res.down){
 58         printf("%lld %lld/%lld",res.up/res.down,abs(res.up)%res.down,res.down);
 59     }
 60     else{
 61         printf("%lld/%lld",res.up,res.down);
 62     }
 63     if(res.up<0)
 64         printf(")");
 65 }
 66 void output(Fraction a,Fraction b,char ch){
 67     showFraction(a);
 68     printf(" %c ",ch);
 69     showFraction(b);
 70     printf(" = ");
 71     switch(ch){
 72         case '+':
 73             showFraction(add(a,b));
 74             break;
 75         case '-':
 76             showFraction(sub(a,b));
 77             break;
 78         case '*':
 79             showFraction(multi(a,b));
 80             break;
 81         case '/':
 82             if(b.up==0)
 83                 printf("Inf");
 84             else
 85                 showFraction(divide(a,b));
 86             break;
 87         default:
 88             printf("error");
 89             break;
 90     }
 91     printf("
");
 92 }
 93 int main()
 94 {
 95     Fraction a,b,ans;
 96     while(scanf("%lld/%lld %lld/%lld",&a.up,&a.down,&b.up,&b.down)!=EOF){
 97         a=reduction(a);
 98         b=reduction(b);
 99         output(a,b,'+');
100         output(a,b,'-');
101         output(a,b,'*');
102         output(a,b,'/');
103     }
104     return 0;
105 }